Andy Pye examines the future of new technology in ultra-capacity polymer supercapacitors and whether they are a viable alternative to EV batteries.
Electric Vehicles (EVs) are coming — and in force. Navigant Research forecasts EV sales will rise from 2.6 million last year to more than 6 million in 2024. There are already over 60,000 home charge points for electric cars in the UK, and new research finds these sockets will be one of the most desirable features of neighbourhoods in 20 years’ time.
Up to now, it has been assumed that electric cars would be battery operated and hybrid vehicles will form a major part of the market. But what about the potential for an alternative technology – supercapacitors? Both batteries and supercapacitors are electrochemical energy storage media, but they are as different as night and day. Both are capable of energy storage and targeted energy release – and yet there are major differences between the two. Batteries store very large amounts of energy that is released slowly but constantly.
By contrast, supercapacitors can only store small amounts of energy (they have poor energy density per kilogramme) but they release this energy much faster and more powerfully with large short-term peak currents. Nevertheless, they have, until now, been unable to compete with conventional battery energy storage in many applications.
Now, a major scientific breakthrough based on groundbreaking research from the University of Surrey claims to have discovered new materials offering an alternative to battery power and between 1000 and 10,000 times more powerful than existing supercapacitors. Patents on the new materials have been filed by a company called Augmented Optics and its wholly owned subsidiary Supercapacitor Materials, registered specifically for the purpose of commercialising them.
Supercapacitors with these properties would allow electric cars to travel similar distances as petrol cars, but without the need to stop for lengthy recharging breaks of typically six to eight hours. Instead, they would recharge fully in the time it takes to fill a regular car with petrol. Very high energy density supercapacitors would also make it possible to recharge a mobile phone or laptop in just a few seconds.
The technology has been adapted from the principles used to make soft contact lenses, which Dr Donald Highgate (of Augmented Optics, and an alumnus of the University of Surrey) developed following his postgraduate studies at Surrey 40 years ago. The research programme was conducted by researchers at the University of Surrey’s Department of Chemistry, co-led by Dr Ian Hamerton and Dr Brendan Howlin. Hamerton continues to collaborate on the project in his new post at the University of Bristol.
The materials are known as hydrophilic polymers. They are based on large organic molecules composed of many repeated sub-units and bonded together to form a three-dimensional network. The test results from the new polymers (Table 1) suggest that extremely high energy density supercapacitors could be constructed in the very new future. Not only that, but the polymers age and show markedly improved conductivity with time – for reasons not currently understood, they self-organise over 30 days (Fig 1).
The patents filed cover the following:
* Conducting Hydrophilic Material + Amino Acid
* Conducting Hydrophilic Material + PEDOT
* Conducting Hydrophilic Material + PEDOT + Imidazole(s)
* Application areas (including bi-directional neural implants
The proprietary materials developed in this project are electrically active hydrophilic polymers: an industrial grade version based on a hydrophilic structure amalgamated with a transparent condiucting polymer called PEDOT:PSS and a higher performance polymer where Imidazole is used instead of the PEDOT:PSS. Imidazole is an organic compound with the formula C3N2H4.
“These *polymers also have many other possible uses in which tough, flexible conducting materials are desirable, including bioelectronics, sensors, wearable electronics, and advanced optics, Hamerton says, now Reader in Polymers and Composite Materials from the Department of Aerospace Engineering, University of Bristol. “The materials can be processed on a large scale by low cost printing technology, offering excellent mechanical properties and the ability of incorporating a large variety of functional molecular structures.”
“We are now actively seeking commercial partners in order to supply our polymers and offer assistance to build these ultra high energy density storage devices,” says Jim Heathcote, Chief Executive of both Augmented Optics and Supercapacitor Materials.
While (almost) everyone recognises the need to replace fossil fuels, as a result of their limited reserves and their effects on climate change, moves to alternatives, such as electric vehicles, have progressed slowly because of practical limitations.
Nevertheless, considerable investment is going into the development of battery systems, particularly lithium ion systems, and incremental improvements are improving the technology. Tesla’s Nevada facility will at full capacity produce enough batteries to power 500,000 electric cars per year by 2020. This is more than the global total lithium ion battery production for 2013.
Lithium is currently the most viable alternative to petrol and in consumer electronics. And it is attracting massive investment. According to global estimates by the US Geological Survey, there is enough lithium in the world – 13.5 million metric tons of it – to last us over 350 years in batteries. Says Nevada Energy Metals executive Malcolm Bell, “It may be time to start worrying about a shortage of lithium, but it’s not a question of whether we have enough lithium — it’s a question of tapping into new reserves.”
Now, the advent of a new system which is not only able to displace batteries, but be a direct and viable competitor to the petrol engine has potential repercussions almost too large to contemplate. Reliance on oil-based transportation could disappear, if not overnight, within a relatively short period of time. While oil would still be needed for lubrication purposes, and to manufacture polymers, including those of which the supercapacitors themselves are made, demand for this commodity could shrink markedly.
While many would say that burning oil for transportation is a heinous waste of a valuable commodity, moving away from it would have major implications for the world order. What effects might it have on the economies of oil-rich countries, such as the USA and the Middle East, and how might they react to the new competition?